Electric furnace machine



Sept. 24, 1946.

H. A. STRICKLAND, JR

ELECTRIC 'FURNACE MACHINE '9 shams-sheet l Filed March 2l, 1941 JNVENTOR Harold riddond lr.

ATTORNEY Sept 24, 1946.

H. f?. sTRlcKLAND, JR ELECTRIC FURNACE MACHINE Filed March 2l, 1941 9 Sheets-Sheet 2 INVENTOR 'Harold Strickland JK FINN x l l v Ilm 1mm. w Hmmm.

A TTORNE Y Sept. 24, 194e.

H. A. STRICKLAND, JR ELECTRIC FURNACE MACHINE Filed March 2l, 1941 9 Sheets-Sheet 3 Sept.` 24, 1946.

H. A. STRICKLAND, JR ELECTRIC FURNACE MACHINE Filed March 2l, 1941 9 Sheets-Sheet 4 Sept. 2 4, 194@ H. "A, sTRlKLAND, JR

ELECTRIC FURNACE MACHINE 9 Sheets-Sheet 6 Filed Hatch 2l, 1941 INVENTOR Harold AScrddnnd .In

ATTORNEY Sept 24, 1945- H. A. sTRlcKLAND, JR n 2,408,350

v ELECTRIC EUENACE MACHINE 9 Sheets-Sheet '7 Filed March g1, 1941 Sept. 24, 1946. H. A. sTRicKLAND, JR?

lft'JCl'RIC1 FURNACE MACHINE Filed March 21, 1941 9 sheets-sheet a H. A. STRICKLAND, .JE ELECTRIC FRNACE MACHINE Filed March 2l, 1941 www A JORAY Patented sept. 24, i946 2,408,350

UNITED STATES PATENT OFFICE 2,408,350 ELECTRIC FURNACE MACHINE Harold A. Strickland, Jr., Detroit, Mich., assignor, by mesne assignments, to The Budd Company, Philadelphia, Pa., a corporation of Pennsylvania Application March 21, 1941, Serial No. 384,503 8 Claims. (Cl. B19-13) My invention relates to furnaces for .heating housings with the automation and the indicating by electromagnetic induction, and particularly to and signalling systems, particularly in the latter those which can be used orare intended for use case in such manner that the high-frequency in the heating of bar or billet stock for forging high-voltage power cannot |be applied to the machine, save that the housings closures are comof .either solid or tubular form, and either circuplete. lar or angular in cross-section, is inserted within It has been an aim to render the furnace most a coil adapted to be supplied with power from an easily manipulable. rihe mere act of loading alternating current source, usually a high-frethrough closure of .its loading door initiates the quency' alternating current source of considerable 1o automatic cycle. Reloading iS required in the VOltige, and the power ybeing turned on to the coil, event of a completed cycle. heating currents are set up within the ymass of the Handling of the workpieces into and out of the bar or billet to be heated due to the electrofurnace is provided for by constructions and magnetic induction from the coil itself. These mechanisms in a manner which aioi'ds ease, currents heat the bar or billet to a forging temsafety, and certainty Vto the operato-r, Safeguards perature. Such a bar or billet is commonly called the heating coil and its workpiece supports from a woikpiece The objects of my invention follow. damage by heavy stock and assuies delivery of Outstandingly I aim to .make such a furnace a the woikpiece 1n best condition with gieatest machine. rrhis I achieve through the .construcpromptness under uniformly obtaining temperation, organization, and automation of its various tures. component parts, e. g., the heating coil into which The attainment of constructions through which the workpiece is thrust for its heating and all one and the same machine may be used to heat appurtenant devices. I have aimed to achieve woikpiece stock of a wide range of dimensions outstandingly adapted for installation in con- I have done with a very maximum degree of simnection with high-speed production systems and plicity and resultant facility of change.

11H65 CO'mmOH in OdaYS industry. I have endeavored also to arrange the various Reliability, uniformity of heating, consistency, assemblies and subassemblies of the machine so and continuousness of operation have been imthat they may be iemoved and replaced in eniportant ends which I have had in view. Conciently handled groups of Darts t0 the ends 0f struction and ari angement of parts, and autosimplifying and facilitating repair and replacemation have also played an important part in the ment, testing, exchanging between one machine attainment of these ends. Automation and coorand another, and of course efficiency of initial dination of automation in interlocking of conmanufacture. trol elements have enabled me to attain these Other objects and full ampliications of the ends to an extent practically eliminating the perforegoing outstanding objects will be fully apsonal equation of the operator, and likewise parent upon cnes acquiring that understanding eliminating disturbances of these several factors, of the invention which is afforded by the aC- i'eliability, consistency, and continuousness, occompanying drawings and the following detailed casioned by disorders of any kind emanating from 40 description thereof. whatever source reaching the machine. There is delineated in the drawings that em- It has been an object too to provide a system of bodiment of my invention now best known to indicators and signals which not only .portray in me, but it will be quit@ apparent that it is suba simple and unmistakable manner all of the conject to yet other embodiments. ditions under which the machine is operating or Of the drawings: HOt Operating, as the case may be, which may be Figure l is a side elevation of the machine of my necessary for its intelligent use to the above ends, invention with the principal parts enclosed by and moreover such a system of indicators and the housings of the machine. The heating coil signals which themselves demand any `necessary is shown in dotted line in the upper DOItOH 0f the attention of thel operator. housing. while the door normally closing the low- I have sought safety in the use of such a Inaer ypart of the housing, has been removed to show chine through appropriate housings of all of its a bank of condensers connected with the coil; high-frequency high-voltage parts, not to men- Figure 2 is a front elevation of the machine; tion effective insulation of them from the hous- Figure 3 is a vertical section on line 3 3 of ings, and the coordination of the closures of such 5,5 Figure 2, in a plane which includes the axis of nipulated ope Ain diagram its c the heating coil, outstandingly showing the heating coil and its immediate mounting and housing, the remaining portions of the machine being broken away;

Figure 4 is a transverse section, transaxial to the heating coil, taken on line 4-4 of Figure 3 looking in the direction of the arrows;

Figure 5 is an enlarged horizontal cross-section of the heating coil in a plane including the axis of the coil;

d elevation of a detail of the the detail of the mounting of the work-supporting rails which lie within the coil;

Figure is a to that of Figure coil and accompanying workpiece supp the coil.

Figure 11 is a transaxial cross-section similar 6 applying to a modified form of orts within partial horizontal section on line H-H of Figure 1 looking in the direction of the arrows to show the banks of condensers mounted in the base of the machines and the bus bars through which they are connected with the source of power and with the heating coil.

Figure 12 is a diagram of the water-cooling conduits and circuits and their included devices connected with the automation system, as applied to the various instrumentalities of the machine, e. g.,

- work coil, condensers, etc.

Figure 13 is a rear elevation of the mechanism having to do with workpiece gauging and locating," workpiece push-out, and magnetic core mounting, the vie-w being taken substantially on line 13--13v of Figure 1 looking in the direction of the applied arrows.

Figure 14 is a side elevation of the mechanism of Figure 13 taken approximately on line lli-I4 'of Figure 13 looking in the direction of the arrows.

Figure 15 (see the sheet containing Figures 11 and 18) is a view on line l'--l 5 of Figure 11 showing a detail of the bus bar connections appearing in Figure 11. Y

Figure 16 is a side elevation of the pedal-marating device for the mechanism of Figures 13 and 14, the View being taken approximately on line lG-l of Figure 2, and showing onnection with the mechanism of Figures 13 and 14.

Figure 17 is a side elevation with portions in Vaxial section of the push-out device such as used in the mechanism of Figures 13 and 14.

Figure i8 shows in front elevation the door to the furnace which governs access to the heating coil and the associated control cabinet, with portions in section and removed, the View being taken substantially on line 18-18 of Figure 1 looking` in the direction of the arrows;

Figure 19 is a diagram of the electrical interconnections between the various instrumentalities through which the objects of automat-ion, condition indicating, safety, etc., are attained;

Figure 20 is a diagrammatic plan View of the arrangement of the condenser units, 'their connections and their terminals within a single so called can of condensers.

Figure 21 on the sheet carrying Figure l12 is, a

perspective view of a bridge-piece connected with a heating coil support clamp.

Figure 22 on the same sheet is a transaxial segmental section showing the bridge-piece of Figure 21 in use in connection with a special heating coil;

Figure 23 appearing on the sheet containing Figure 4 is a fragmentary rear end view of a heating coil showing means for securing workpiece guide rails in connection with the special coil of Figure 22; and

Figure 24 is the diagrammatic illustration of a modied form of the magnetic core.

Referring now to the drawings, Figures 1 to 4, particularly Figures 1 and 2, it will be observed that I have made the frame and housing of the furnace machine 3E) generally of L-shape as viewed in side elevation, and in form not unlike the operators switchboard of a manually-operated telephone system. This is to say that the frame and housing comprise a horizontal branch 3| having a horizontalv table-like top 32, and a vertically extending portion 33. I shall not go into the details of frame members and panelings of this frame and housing further than to say that it is constructed of metal of a strength adequate to support the parts which I show and describe as supported thereby and housed therein. Front, side and back door openings 34, 35, and S6 (the latter not shown in form, although it is intended to extend the full length of the back of the housing 3G) are provided for ready access to the various instrumentalities supported by and housed within the casing 34, and these openings are provided with suitable closures such .as that 31 sh-own in the door opening 34 of the front of the casing, which closures may be provided, as is common, with suitable hinges and locks for ready manipulation and locking. An opening 38 in the top 32 of the table-like portion 3i is closed by'a cast foundation member 39 which mounts the heating coil 4G. An opening 4l in the lower section of the vertical portion 33 of frame .313 is closed by a backplate 42 which mounts the workpiece gauging and ejecting mechanism and the .magnetic core of the coil. An opening 43 in the upper section of the vertical portion 33 of the frame is made for the mounting of the signal and instrument board (not shown), and is closed by this board when it is in place. Openings 44 in the lowermost portion of the casing are guarded by grillworks 45 through which the housing 3! is ventilatedthrough suitable apertures in the `upper parts of the housing (not shown). rThe hood 41 is provided with side and top Ventilating openings 48 and 49. A front-plate 5D rising from the region of the foundation plate 39, coacts with the rear-plate 42 in supporting the hood 4'5. The front plate closes the otherwise open front end of the hood 41. The foundation plate 3S, the coacting and surmounted back and front plates 42 and 50 (also castings preferably) and the hood and irst to 41 together constitute a housing unit individualV to the heating coil 44 and its immediate appurtenant parts. The front plate 50 is provided with an opening 5i through which the workpieces are fed to the furnace by projecting them axially of 4the coil 4U. A hinged door 52 closes or shrouds this opening during the heating operation. n

A bus bar system 53 is housed in the portion 3l of the housing 30 just below the foundation plate 39 and tabletop 32. It is connected at 54 by suitable buses to a source of power through a contactor mounted in the cabinet (not shown) ,and by leads 55 extending vertically downward 7 5 to the banks of condensers 56 which are mounted by porcelain insulators 51a on a system of rails 51 mounted transversely of the section 3l of the housing.

Stock-gauge and push-out mechanism designated 58 and shown as mounted on the backplate 42, is accommodated within the vertical portion 33, as clearly appears in each of Figures l and 3. The pedal-operated actuating device 59 of this mechanism is, however, located in the bottommost part of the front section 3l of the housing and connected to the mechanism 58 by a conduit 60. The conduit 60 is preferably an overlong rubber hydraulic tubing whereby device 59 may be removed for services without removal of hydraulic uid from the system.

Also housed within the vertically extending portion 33 of the housing 30 are the systems of water-cooling connections and their app-urtenances, the subject of Figure l2, and the system of electrical control including its various instrumentalities as illustrated in Figure 19. There is room in the rear part of the housing 3l! to house a power transformer. The lowermost part of the vertical section 33 houses the contactor and such connections as are needful to connect it to the workpiece within it are of a Very special conit? struction which appears oustandingly in Figures 3 to 9. The coil per se 40 is comprised of hollow conductors 6I generally of square shape. Cooling water in suiiicient volume to cool the coil itil is passed through the hollow 62 of this conductor. Individual turns of the coil (see particularly Figures 5 and 8) are insulated from each other by a spiral of mica 63 or the like, or else the conductor throughout its length may be wrapped with an insulating tape of an appropriate character, preferably heat-resisting, suitably impregnated with a suitable varnish after the winding of the tape is complete. If the conductor is so wound, then when the coil is wo-und on a suitable mandrel, there results inside and outside insulation 64, 65, as well as insulation 53 between the turns. The coil is wound on a suitable mandrel (not shown) preferably a collapsible mandrel. However, initially there is placed on a mandrel an innermost cylinder of high-grade mica sheets B capable of high-heat resistance and impervious to moisture and bonded with a resilient insulating varnish. Also superimposed on the innermost cylinder of mica 66 is a secondary cylinder of mica 61 which may be composed of "micanite or other composite or compounded mica also bonded with varnish. Figure 8 is a section of one end of the coil, the right-hand end, as it appears in Figures 3 and 5. From this it will be seen that micanite cylinder 61 is shorter by a fraction of an inch than the mica cylinder 56, and that the endmost turn B8 of the coil B lies axially inwardly of the end of cylinder 61 a fraction of an inch, thus aording a stepped construction of the insulating cylinder ends. Coil 4] as insulated at 84, 65 is wound directly upon cylinder 6l. Before the segmented strips are laid on, the coil is wrapped in a single layer of bonded mica set in varnish. This provides a very important seal against moisture if such should collect in the voids between the outside segments 69. Laid axially upon the exterior of coil 4l! are segmental strips 69 of Micarta, Bakelite, or the like, which together completely encase the outer periphery of the coil 40. These longitudinally extending insulating strips 69 are bound in place by overlapped turns l of insulating tape given a water and moisture-proof treatment and baked. The opposite ends of the insulating strip 69 are provided with jogs 'Il radially juxtaposed to the stepped ends of the insulating cylinders 66, 61. A series of mica rings l2 are laid over the end of cylinder 61. and against the end turn B8 of coil 40, and a unit insulating ring of Micarta or Bakelite i3 is laid over the end of mica cylinder BS, these rings completely filling the spaces between the endmost turn 68 and the ends of cylinders 66, i5l on the one hand, and of the strips 59 on the other. They are sealed in position by coating and baking with a resilient insulating compound. In such fashion the coil 49 is made and hermetically sealed inside, outside, and at each of its ends whereby heat may not crack the insulation, and moisture may not penetrate it.

Heat is prevented from being directly radiated from the red or white hot surfaces of a workpiece being heated to the mica insulating cylinders S6, 61 by an annular lining of insulating rebrick 14, also shown in Figures 3 to 5 inclusive. This lining of flrebrick like the insulating outer covering 59 is comprised of longitudinally-laid segments. However, instead of conjoining the end edges and hermetically sealing together by intervened baked insulating compound, as in the instance of the bars 69, the individual segments 'l5 of this lining are spaced from each other by water-cooled work-supporting rails 15 intervened between them, and so constructed as to hold them radially outwardly against the surface of mica cylinder 55. To this end the opposite side edges of the segments 15 of the insulating lining (preferably comprised of a high-grade insulating irebrick compound) are chamfered at Tl, the chamfer terminating in a slight jog '18, and the rails 1S are provided with welded-on sheet m-etal holding clips 19 of the form having a branch extending on each side of the rail 'I6 at the angle of the chamfer Tl whereby to lie flatly against the chamfer and within the depth of the jog 18.

The rails No are held radially outwardly by three sets of supports, one at the middle and one at each end. That in the middle is shown especially in Figures 5 and 6 to comprise an expanding ring de or" sheet metal. The ring is formed of the overlapping wings Si of sheet or strip stock welded respectively to opposite sides of the rail To, and joined in their overlapping portions by a clamping screw connection 8?: having an appropriate lost-motion connection (not shown) between the overlapped ends permitting the eXpansion of the ring 30 to a diameter which moves the rails 'i6 toward or against the inner surface of the mica SS, and retains them in that position when the devices S2 are tightened up. Each of these joints is insulated by a set of amber mica washers 22a. These washers will stand a temperature of 1CGO C. If these were not insulated, the ring would act as a short-circuited turn of a transformer.

The devices at the opposite ends of coil 43 are diierent. At the upper or right-hand end of the coil 4E) as illustrated, there is secured to each rail an outwardly and radially extended supportstud These studs are passed respectively through slots or holes, as may be preferred, in the outer ends of rails of metal or insulating material (such as Bakelite or Micarta), the rails `iil being laid longitudinally over the length ci the exterior of coil 4o to project slightly beyond each end. As shown, the rails are of charnel cross-section to aiord less generation of eddy currentsv as well as lightness with strength. At the opposite end (the left-hand end, as shown) the projecting ends of work-supporting rails 'I6 are engaged within the loops 85 of screw-hooks 8S, the threaded outer ends of which are carried radially through apertures or slots in the opposite ends of the rails 84, there being preferably though not necessarily one securing rail Sil for each worksupporting rail 76. When the nuts 81 respectively on the ends of studs 83 and screw-hooks S6 are tightened up, they hold the outer ends of the rails 16 toward or against the inner surface of the mica cylinder 66 as does the expanding ring 8G. Thus the rails 'le are held in position throughout their length and rmly hold the rebrick lining 'l5 in place. There may be provided as many expanding rings 8|] as are needful to meet the requirements of coil length.

The securing clips 19 are not of an adjacent continuous series. They are separated by wide intervened spaces. In these spaces there are edgei welded in the radial planes of the coil axis A/A to the tubular rails 16, an intervened series of workpiece supports 88 in the form of sheet or strip metal ns whose lengths are axially extending. Their leading edges are chamfered as at 89,`to prevent obstruction to the movement of a workpiece being inserted Within the coil. They are spaced slightly at each end from the inter- Vened irebrick securing clips 19. Their radially inner edges 9S are parallel to the axis of the coil GS though not radially equidistant, and their locus is a cylinder of radi-us R whose center C is eccentrically above axis A/A of coil whereby the axis of workpiece of radius W coincides with axis of coil. (See Figures 6 and 7) the locus cylinder of center C is slightly greater than the diameter of the heated workpiece to provide tolerance suciently greatv toprevent binding due to expansion. Rails 16, clips 19, expanding rings "8G, and work-supporting fins 88 are all of high heat-resisting metal, especially ns 88. Water is continuously circulated through the tubular rails 16 in pairs in series, or in series as a group, the connection being generally illustrated by a dotted line connection 9| between the two outermost tubes 16 of Figure 5 shown as provided respectively with inlet and outlet openings 92, 93 at the opposite ends of rails 16. Inlets and outlets are each provided with moisture-discharging lips or flanges 94 which prevent accumulated moisture from running down the rails into the coil.

The entire system of equidistantly spaced polygonal workpiece-supporting rails 16 and lirebrick lining may be bodily removed from the interior of the heating coil 45], by simply removing nuts 81 and the screw-hooks 3E, radially removing bars 84, and drawing the ensemble axially outwardly (that is to say, to the right in the instant case). This enables the replacement of worn or broken rebrick segments 15, and repair to any of the rails which may for any reason need repair. To facilitate this the expanding ring 80 need not quite expand the rails 16 and the rebrick segments 'l5 into contacts with the inner mica cylinder 65, but provides such tolerance as will ena-ble the ensemble to be slid longitudinally outwardly without intermediately releasing the clamp-ing screws 82. Ring 80 and the connected rails are readily adjusted to tolerance diameters by tting to a suitable mandrel and checking by a sizing ring before placing in the coil. However, if need be, a suitable tool will enable the The diameter ofV clamping screws 82 to be reached, and one or more of them released. The individual segments l axially separated in the middle by the expanding ring 8!! may be individually placed in position or axially withdrawn from the inner or the outer end of the coil, as the case may be, merely by loosening the respective screw-hooks 86 and studs 533 once the expanding ring 8B provides the proper tolerance at their axially inner ends. Thus removals and replacements may be made without removing the ensemble. All of this, of course, is readily achievable when the heating coil and the workpiece-supporting rail ensemble are disassociated from the housing. However, all of these operations may also be achieved while the coil and rail ensemble are in place on the machine, merely by removing hood 4'? and front plate 5u and its supported parts as a unit. They together constitute aunit sub-assembly and may be slid oir forwardly.

Heating coil lil with its workpiece supporting appurtenances is mounted with its axis coinciding with a general horizontal axis A-A of the furnace machine, by supporting it from coil centering C-clamps 98 carried from and forming a part of pedestals Q9 erected upon and secured to the cast foundation plate 39 of the table-portion 32 of the housing. There are two (or more in case of large coils) of these coil-supporting pedestals 9S spaced apart an adjustable distance to support coils of a number of diierent axial lengths without relocation upon the foundation plate 39. A reference particularly to Figures 3 and 4 will make clear their construction. The lower portion of the pedestals 39 has a plane of symmetry coincident with the vertical plane of the axis A-A upon which the coil 4|) is to be centered. It terminates a considerable distance below the axis A-A, a distance sufficient to permit the accommodation of coils d!! of a number of different sizes. It is provided with integrallyformed right and left branches Illu, IGI making equal angles with the vertical plane V-V of axis A-A. Threaded through the arms |00, ||l| on radial lines intersecting axis A-A are radially adjustable coil supporting studs |02, l U3. The heads of these studs |02, m3 are located toward coil 49 from the arms |00, lill, and support the coil directly upon pads of insulating material I U4 secured to the heads. Thus by relatively adjusting studs m2, H33 the axis of a coil All of any accommodatable diameter may be placed directly upon the horizontal axis A-A of the furnace machine. In this case there is provided only one securing bar Sli for two rails 7S, the two rails being bridged together and to the bar 84 by lateral extensions 34a and Sb having a rigid insulated connection with bar 34 and taking at their opposite ends the studs 83. Thus there is space 60 for pads |34 directly to engage the coil, and more importantly rails 16 may be removed While the coil :lil is yet firmly clamped in position.

The G-clamps 93 of these supporting pedestals are comprised of C-arms, as clearly appears in 65 Fig, 4, forked at their lower ends |05 to straddle the lower portions of pedestals 99 and be pivoted at |235 on the opposite side of the vertical plane V-V from the body of the C-clamp. When the clamps 98 are in clamping position, their upper 70 ends lill lie in the vertical plane V-V, and are provided with'a threaded adjusting stud |08, the head it of which lies toward the coil 40 from the upper end IG? with the axis of the stud in the vertical plane V-V.

Beyond the head |68 projects a reduced extension of the stud H2 on which is radially slidably mounted a bridge member H3 carrying at its opposite ends pads oi insulating material H3a. A spring H on the reduced section H2 and intermediate head |99 and bridge H3, presses the bridge toward the coil 49 to achieve yieldingly the clamping of it, while a washer and cotter prevent the radially movable bridge from dropping from the reduced extension of the stud H2 when the clamp is released.

This clamping arrangement is not only adapted for clamping the coils of different diameters merely through the radial adjustment of stud |08, but also to clamp under different pressures through the adjustment of spring H0. Yet further, however, the structure of bridge member I I3 is such that merely by rotating it on the reduced Xtension H2 of stud |98, it is adapted t0 engage with the top of one of the rails 84 instead of engaging between rails 84. See Figures 21 and 22 in this connection. Examination of these will show that pads ||3a are elongated and provided in their middles with slots H317 of a dimension adapting them to lit over the top of a rail 84 when bridges I i3 are rotated ninety degrees from the position shown in Figure 4. Thus coils having any desired arrangement of bars B4 may be used, and the smaller coils in which there are but three or four rails 16 and accompanying bars 84 may be accommodated as readily as the larger ones.

The arm HH of the lower portion of pedestal 9: is extended laterally and widened in a vertical plane to form a mounting pad H5 for the bus bars llt through which the power is applied to the opposite ends of the work coil 49. These bus bars Ht are two in number connecting one with each end of coil d0 through a bolted-on connecting clip H1, bolted flat against the side of the bus bar, and having a clamping connection H9 with the laterally-extending terminal H9 of the ccil lid. The bars are insulated from each other and from the mounting pads H5 by blocks of insulating material |29, the outermost of which is utilized as a clamping plate to bolt the bars together and to the pads H5. There being two pedestals 51 and two pads H5, the buses H6 are rigidly supported in a horizontal position laterally of the coil, but parallel thereto.

The foundation plate or base 39 upon which the coil :it is mounted through the pedestals 99 is, as has been said, a casting in this embodiment of the invention. It is formed with its upper face l2! on either side of the pedestals, slightly downwardly and inwardly inclined toward the vertical plane V-V whereby collected foreign matter or moisture will gravitate toward the center of the plate from both sides and from each end, the ends being similarly inclined. At the center of the plate and surrounding the region of mounting ci the pedestals is an endless groove |22 which keeps moisture away from the pedestals and prevents its creeping upon them. The center of the casting is thus a pad |23 upon which the pedestals are mounted. Groove |22 communicates at its axially inner end with a drainage conduit |213 suitably connected to a drain, as will hereinafter appear. The under-margins |25 of base 39 are nnished to rest upon the top of table 32 and be secured thereto by suitable bolts. The sides |26 are also iinished and receive in overlapping relation the lower edges of the hood 41 secured thereto by suitable cap screws. These and no other screws are removed when it is desired to remove the hood and front plate assembly. The ends |21 of the plate receive in overlapped relation and bolted thereto if desired (bolts not shown), the end plates 2 and '59, thereby vertically aligning them with respect to the base 39.

Located centrally of the base and upon the plane of symmetry V-V, is the aperture 49 previously referred to, tlircugh wl ich the connections are made from the source of power connected with buses 5d and 53. The rectangular system of buses 53 emanates from concentric tubular conductors |28 lying in the of symmetry V-V and supported at its ends (or perhaps supporting) le rectangular system 53', each one of the tubes |28 of the concentric conductors being connected with one of the bars and hence with one of the buse ed. Vertical risers |29 from the concentric conductor |22 emanate therefrom through nested connectors |30, each connecting one branch oi the riser |29 to one branch oi conductor ida. nsulation 46a protects them from ground on plate 39. As clearly appears in Figures 3 and 4, particularly in Figure fl, the inner of the connectors |39 connects the inner branch o riser |29 with the central portion of a continuous branch of conductor |28, the inner branch, while the outer connector |39 connects the juxtaposed ends of the two-part outer branch oi conductor |23 to the outer branch of the riser |23. Their ccnnectors |3| respectively space the branches of concentric conductor |29 apart from each other and maintain them apart through their connection with the branches oi the bus system 53, or vice versa, the connectors |39 to the riser being rigidly maintained in spaced relation through the intervention of a spacing sleeve |32 of insulating material between the branches of the riser |29. This insulating material itself if sufficiently solid and rm in its seating, may be suicient to retain all the parts of the bus and conductor system 53, 54, |25, |29 in spaced relations, insulating the various branches from each other. The bars oi the rectangular system are, as shown clearly in the plan View oi Figure ll, bolted to the respective connectors i3| at each end.A Thus the entire ensemble becomes a unit which may be separately fabricated and installed in the machine. At their upper ends the branches of riser |29 are respectively joined by clampedon connectors |33 to the bus bars H. Connectors |33 are angle-shaped extending radially laterally of the branches of riser |23, and then upwardly t0 have their outer ends respectively bolted to the buses H9. The axially inner set of connectors |3| of the ensemble on the other hand, also angle-shaped, have their axially inwardly extending branches bolted respectively to the bus bars 54 connecting with the source. Unbolting of this connection and unclarnping of connectors |33 at the riser |29 enables the ensemble to be bodily removed. Itis to be noted that the closely spaced relations of the concentric conductors |29 and the at bars of the rectangular system 5S of the ensemble, as well as the nested and concentric relation of the parts connected with riser |29, and the duplex connections thereof to the outside bus, are such as to develop a minimum of impedance.

The ensemble is shown particularly in Figures 1, 2 and 4 as also directly connected with the banks of condensers 55 beneath them, the connection being by means or a system of vertically extending jumpers |34 respectively connecting the terminals of the condensers with one or the rows of condenser units 139 of each row.

11 other of the branches of the rectangular bus system 53. The ring bus is supported from base 39 by tie rods 39a which clamp the ring bus between Wooden separating blocks 39h. The relative arrangement of the condensers and their relative dimensions as respects the bus system 53 is such that the jumpers 134 are extended vertically upward from their terminal connections to engage the bars of the system 53 in Vertical overlap. If desired, however, additional such support may be provided by suitable insulating blocks 135, the arrangement of two of which is suggested in Figure 4. Referring particularly to the plan View of Figure 11 in conjunction with the sectional elevation of Figure 4, it will be seen that in addition to having the rectangular bus system 53 encompass the entire bank of condensers and effect convenient connection of each individual condenser thereto through vertical jumpers 13d, I haverdevised an arrangement of L the opposite terminals 13S, 137 of the condenser units within each so-called can 133. Upon the top of the can and in a plane substantially parallel to the plane of the bus bars 53, I can effect adjustment of condenser capacity and voltage with greatest facility. As clearly appears in connection with the upper right-hand can 13S in dotted lines, two groups 139 of condenser units of a given capacity and voltage, each having one terminal connected to a common lead 1110 which 1 is connected in common with the terminal 131 for which five connector bolts are shown adapted to join such terminal to one of the vertical jumpers |34. The independent terminals of each unit of each group are brought independently to one of the six independent terminals 13E, The terminals 135 are arranged in two parallel rows lying toward one side of the can, while independent terminals 133V are arranged in two parallel rows lying toward one side of the can and common terminals 131 are arranged toward the other end of the can. n plan the axially extending branches of bus bars 53 pass midway between them whereby a vertical jumper 134 may conveniently connect with one of the independent terminals at the same time that another jumper |34 connects with a set of common terminals |31. Sets of transversely extending jumpers lll! of uniform dimension and of such length as to span from one independent terminal to the next adjoining of a transverse series of condenser' units |39, enable the units of any given series to be connected in parallel with each other, and through the common lead 149, in parallel to the bus bars of system 53. Sets of axially extending jumpers 1512 of uniform dimension and of a length enabling the adjacent groups |39 of adjacent cans |38 to be interconnected in series, span adjacent terminals of such groups. Thus as appears in plan view of Figure 11 particularly, adjacent independent terminals 13'1 of adjacent cans 138 have been generally connected together, with the exception of certain units or groups in the cans of the upper right of the View. When connectors |35 are applied, as shown in the remaining units, and connectors 131i are applied as shown, this results in placing across the bars of the system 53 ten rows of condensers, three units 139 in each row. Thus adding jumpers to include the remaining terminals 13'1 in the same manner as those already connected with jumpers, would result in so placing twelve Numerous other combinations are readily attainable merely by adding and subtracting jumpers, or by Vusing various combinations of jumpers.

-13`1 would be omitted and one axially extreme set of jumpers 136 would be connected to one bus of the system 53 by one jumper 134, while the paralleling jumpers at the opposite end of the bank would be connected by another juniper 134 to the other of the bars of the system 53. Thus there would be provided sii/:cows of six units 139 each connected with the`- Lilus bar system 53. These are but a few of numerous readily attained arrangements chosen for purposes of illustration to show the facility with which the voltage and capacity can by this arrangement be adjusted to the requirements of Work coils of a wide variety of sizes. i

The stock-gauge and push-out mechanism 58, 59, and the magnetic core 9'1 of the coil 40 associated therewith, all coact with the axially inner end of the workpiece at or near the axially inner end of the coil 413. While they are located generally in Figures 1 and 2, their detail is depicted generally in Figures 3, 13, 14, 16 and 17. Referring particularly to Figures 3 and 14 for the moment, it will be seen that th'e stock-gauge per respect to the axially inner end of the coil 4Q,

thereby to engage an inserted workpiece in different axial positions within the coil 40. Once adjusted for the proper gauging of the stock, for

'the proper heating thereof through the proper length, the gauge arm 143 may be firmly clamped in its supported position. (See Figure 3.)

Mounted on this adjustable arm |43, shown in Figure 3 as being iixedly mounted although it may be adjustable, is magnetic core 91 comprised of an annular series of radially-extending, radiallytapering laminations, the details of which are no part of the present invention and are, therefore, not shown. Sufficeth to say, they are bound in place upon the support 143 or equivalent support by any suitable means such, for example, as the commonly known interlocking tongue and groove device 145. diameter and axial extent. Therefore, a consid- Verable magnetic mass is shown as of approximately the diameter of the workpiece accommoldatable by coil 411.

As projected in juxtaposition to the end of a workpiece, it receives the flux flowing external to the coil 40, collects and concentrates it, and conducts it more or less directly 4axially inwardly of the inner end of the Workpiece. Its utilization and relative adjustment with respect to th'e end of the workpiece very considerably reduces the reluctance of the magnetic circuit and aords a very flexible control of the distribution of heat in the heating of the axially inner ends of the workpiece. Thus with 'the proper gauge of the stock in position within This magnetic core is of considerablev The push-out mechanism comprises a preferably though not necessarily water-cooled pushout rod |46 working axially back and forth within the tubular workpiece stock gauge and support |43. It will be noted by reference to Figure 17 that this rod is water cooled all the Way to its tip |41 by means of an internally-laid water-injection tube |48 which enters its tubular body by Way of an elbow |48 connected with its rear end through a coupling |46. This water discharges through the main body of the rod |46, externally of the injection tube |46, through coupling |49, and through a hollow |56 in the elbow |48 in advance of the threaded connection of the injection tube |48 therewith. Thus the elbow member |43 provides both an inlet connection |52 and an outlet connection |53. The engaging tip |41 of the push-out rod |46 is made of heatresisting metal or other such material, and is preferably removably secured to the end in a manner not shown, but well known in connection with welding electrode tips and th'e like.

This ejector rod |46 is axially projectable through the tubular support and stock gauge |43 by means of the long arm |54 of a bell crank pivoted at |55 and whose short arm |56 is connected with piston |51 of a floating fluid pressure cylinder |58 linked at |56 to a bracket |66 secured vto the rear face of plate 42. The spring |56 moves the arm |56 against the action of the piston and cylinder. Bell crank |55, |56 is itself supported along with other parts of the mechanism from a larger bracket |6| also secured to `the plate 42. Engagement of arm |54 with the ejector rod |46 is a one-way engagement toward the coil through contact of its forwardly bent upper end |62 with an adjustable collar |63 about the rod, whereby the length of the rod may be made sufficiently great to enable it to be used in connection with workpiece stock of various lengths as associated with coils 4! of various lengths, the relation between the tip |41 and the collar |63 being appropriately adjusted to the ejection requirements of stock and coil sizes and positions and stroke of the push-out mechanism at large.

The stroke of the push-out mechanism is achieved by iiuid pressure applied through conduit 66 from a master cylinder 59 of the automobile brake type operated by foot pedal |64. The system is kept lled from the usual reservoir as in the automobile practice. The stroke of cylinder 5S and hence of the ejector rod |46 is regulable by an adjustment of the leverages through which foot pedal |64 is connected to the piston rod |65' of cylinder 59. Pedal |64 is a bellcrank whose short arm |66, to which retracting spring |61 is connected, is adjustably fulcrumed atl |66 upon a fulcrumed bearing bracket |69. Bracket |69, together with pedal |64 and cylinder 59 and appurtenant parts, are all borne from a removable mounting plate |16 bolted to the face of the housing section 3|, whereby the ensemble of this foot-pedal-operated actuating mechanism is removable as a unit from the housing 3| `through the opening |1I, without disconnecting from hose 66, and to the extent permitted by the provided length of flexible hose 66, merely by disconnecting the plate |16. A heel |12 on lever |64 abuts the inner face of the mounting plate |16' at the outer extreme of the stroke. Further stroke adjustment can be had through the screwthreaded adjustment of piston rod |65 with respect to link |13 by means of which it is connected to pedal |64.

Workpiece stock-limiting switch |14 (see Figures 13 and 14) is also operated in connection with the push-out rod |46. This is achieved through the long arm of bell-crank lever |15, |16, which long arm through a forwardly projected end |11 also has a one-way forward engagement with the adjustable collar |63. Like the bell-crank |54, |56, the bell-crank |15, |16 is freely journalled on the pivotal shaft |55. Unlike the bell-crank |54, |56, the arms of which are integral, the bell-crank |15, |16 has its arms relatively adjustable, the short arm |16 being adjustably clamped by a split collar |18 surrounding a lateral extension |19 of the hub of the long arm |15. Arm |16 forms a segment about the axis |55, and on the outer arc-shaped periphery |66 of this segment rides the switchactuating roller arm |61 of the limit switch |14. Bell-crank |15, |16 is biased toward a forward position by a spring |82 extending to back plate 42, and the roller of roller arm |81, when the bell-crank is in its extreme forward position and the workpiece has been pushed out, engages in an arc-shaped depression |63 in this segment. By angularly relatively adjusting the arm |16 with respect to arm |15, the action of limit switch |14 may be adjusted effectively for each adjustment of collar |65. Switch |16 is mounted upon a bracket |64 also borne by back plate 42.

Devices associated with the feeding-in of the workpieces on the other hand, are mounted in connection with the front plate 56 of the housing of coil 16. These are the coil mouthpiece 66 and the door 52 and appurtenant instrumentalities. The mouthpiece 66, as has been said, serves to center the workpieces of bar or rod stock properly upon the axis A-A of the coil 46 and the supporting rails 16. It is by virtue of its susceptibility to removal and replacement from the opening 5|, suited in size to the various sizes of coils and stock. It is suitably bolted in place (bolts not shown) and mounted with a clearance 96o. for radial adjustment to precise position on axis A/A. On its inner side it is provided with f an annulaiseries of Aaxially and inwardly projecting spaced teeth at |65, the inner side walls of which project radially and axially inwardly toward the coil, and the extremities of which have an extent substantially paralleling the axis A/A and lie on a circle substantially of the same diameter as those circles on which lie the inner edges of the work-supporting ns 66, while their inner sides meet their inner ends at a relatively sharp angle. All this clearly appears in Figure 3 and Figure 5. Thereby these teeth guide the stock accurately into engagement with the ns 88 of the supporting rail 16, preventing impingement upon intermediate transversely-extending walls (this through their inclined inner walls and their extremities), and when the workpiece is pushed out, remove from it foreign matter such as light scale which may have formed (this through the sharp innermost edges). Such foreign matter as is removed falls between the teeth or past their inner extremities and upon the hopper plate |66 which discharges through opening |61 to a chute |36 projected from the opening |61 exteriorly of the machine. Thus no scale or other foreign matter drops to the foundation plate 39.

The door 52v which normally closes the mouthpiece opening |89 is hinged on a transverse axis |66 (see Figures 18 and 3) just above the opening 5|, the hinging being achieved through a journalling of the axis shaft |90 at one end in a small exterior bracket' 9| and, at the other, in a journal |92` in a control box casing |93. Like chute |83, bracket |9| and the casing |92 may be cast integrally with the plate 59. However, the control box |93 especially may be separately formed and mounted to facilitate control assemblies therein.` Door 52 is biased to a normally open position in which it is raised vertically as shown in Figure 3 by means of a strong spiral spring |94 on the axis |99 reacting, at one end,

` against the Yfront plate 59, and at the other end against the door 52. However, the door may be latched when moved downwardly against the pressure of spring |94 to engage the end of a latch bolt |95 operated from a latch mechanism within the control housing |93. lThe door 52 is in the form of a hood, as will most clearly appear from an inspection of Figures l and 2, a hood open on its rear and undersides and axially sufciently long to accommodate a considerable length of stock projecting axially outwardly of the mouthpiece 95. Such a hood-like door 52 at one and the same time enables stock considerably greater length than its portion to be heated,y to be handled in and out of the furnace, without interference from the door when in closed position, safeguards the operators from contacting the outer end of a highly heated piece of stock (which, in case of electrical failure in the coil might be at high potential) and, through the substantially flush engagement of its inner edges with the iront -face of the plate 59, prevents somewhat escape of heat by convection. Note especially the position illustrated in Figure 1.

Control box |93 contains a latch mechanism |99 controlling the latch bolt |95 for holding the door in closed position, the door-operated control switches |91, and an electric terminal bar |98. The latch-bolt-operating mechanism comprises spaced guide mountings |99 for the inner end of the latch bolt, and the latch-bolt-operating solenoid 299 connected to operate latch bolt |95 through a bell-crank lever 29|, one arm of which engages with a collar 292 on the latch bolt |95. When the solenoid draws its core up, the latch bolt is retracted and the trap door is sprung upwardly to aord access to the outer end of the stock which it has hitherto shrouded.

The bank of control switches |91 are of the micro type. There are three of them shown in front elevation, numbered, respectively 293, 294 and 295. They are each as shown actuated from the axis shaft |99 through operating arms 2'91 secured by clamp 299 to shaft i 99 and oscillable with it. The shaft |99 is rigidly connected with door 52 by means such as pin connection 298, although any other such means may be used. Thus, when spring |94 moves the door upwardly or when the door is manually moved downwardly, the bank of switches 293, 294, 295 is operated. The control box |93is normally closed by a suitable cover 299 appearing in the front elevation of Figure 2. A small handle 2|9 projected radially outwardly through the cover from bolt |95 aords a means of manually operating bolt |95 independently of the solenoid mechanism 299, 29|. Projection of the latch bolt is by means of spiral spring surrounding the bolt between the collar 292 and the guide |99, as shown.

Viewing now the ensemble of all instrumentalities connected with the housing of coil 49, especially with the foundation plate 39 and the front and rear plates 42 and 59 which are erected thereon, it will be seen that all of these instru- Cil mentalities can be removed as a unit with the housed coil 49, if this be desired, merely by unbolting the foundation plate 29 and the back plate 42 from the faces of the principal housing 39 of the machine, the electrical, water andother connections having been previously broken. It will, of course, be particularly necessary to remove the bus bar system 53 by disconnection at the connectors |39 and appropriate lowering of the bus bars. This makes for convenient major 'subassembly and shifting of such major subassembly from machines to test bench or back, or substituting one such major assemblage from one machine in another, and so forth. Normally, however, the subassembly comprising plate 59, door 52, box |93, and hood 41, is the unit removed, leaving base 39 and plate 42 on the main frame. This alone `gives four-sided access to the coil 99 as clamped in place.

Effective provision is made for water-cooling of all parts whatsoever, such as heat in what otherwise would be an undue measure. This includes not only the coil 49 and its work support- 'ng rails 19 and the water-cooled push rod |46 (mention of the hollow conductors for watercooling of which has already been made), but also the iron core 91, the condenser banks 56, and any transformers which may be used. A coil of water-cooling tubing 2| l is provided about the magnetic core 91 for the purpose of cooling this mass of laminated transformer iron. The internal annular cooling of the push-out |46, as shown in Figure 17, also aids in cooling the core 91. The coil 2|| is closely heat-coupled to the laminations 91 and provided with appropriate inlets and outlets 2|2. The water-cooling system at large is illustrated in diagrammatic form in Figure 12.

Here we have shown a principal water inlet 2 3 projected through a shut-off valve 2|Ll and a large strainer 2|5 to a general machine-distributing main 2|9 extending by appropriate branches to all apparatus to be cooled. Main 2|6 connects with the ingoing terminal of coil 40 at 2|1, with the in-going termini of the rails 16 at 2|8, with the inlet to the cooling coil 2| of the magnetic core 91 at 2|9, with the push-out rod |49 at 229, and with the water-circulating inlets of the condenser banks at 22|. Similar such connections as those made to coil 49 and condensers 59 may be made for transformer coils where transformers are used. The outlet connections of these respective instrumentalities are for the coil 49 at 222, for the rails at 223, for iron-corecooling coil 2H at 224, for push-out rod |46 at 225, and for the condenser banks at 226. These outlet connections connect in common tothe drain connection 221. Inasmuch as electric potentials appear across several of these water ports, it is necessary to make water connections through electrically insulating water conductors. This is done, for instance, in the cases of the heating coil, cooling coil for laminations, -individual capacitors, etc. However, in connection with various of these instrumentalities, there are lprovided control and signal actuating devices intervened between the inlet main 216 and the drainage main 221, respectively. Thus, while the inlet connection 2|1 to coil 49 is made directly with the main 2|6, the outlet connection is by way ofa conduit 228 through a thermostat connection 229 governing a control switch 239 and through a water-ow control switch 23|. Thus, the inlet connection 2|8 to the work-supporting rail system 16 is not, as in the case of the coil 43, direct to mains 2|6, but by way of an electric or other water heater 232 and a branch 233 whereby the water reaching the rails is heated to a temperature such that moisture condensation or collection on the rail 16 is prevented, irrespective of the state of use of the furnace. A bypass 234 from the heated water line 233 to the rail 16 supplies water also to the cooling coil 2|| of the iron core S1. This coil may be supplied directly from main 2|6, if desired, but the connection illustrated is preferable. Similarly flowcontrolled switches like 23| and thermostatically controlled switches like 230 may be utilized and are intended to be utilized in connection either with the condensers 56 or any other instrumentalities where it is desired to individualize indicator switch and machine control due to temperature or now of water connected with such instrumentality. An extra group of such devices 230 is shown unconnected and is intended to represent connection to any other such instrumentalities in the same manner as connected with the coil 4o through branch 222. A pressure-operated switch 235 is connected through pressure diaphragm 233 with the mains 2|6 to indicate through its action the fact that cooling water is on the system. Drain opening |24 of the base plate 39 is connected to a separate drain 231 used to prevent possible back pressure from line 221 forcing water into base pan.

This ensemble of the water-cooling system is, as heretofore stated, installed appropriately within the vertically extending section 33 of the main housing 30 and is, for the most part, mounted upon the rear of the general vertical partition wall 23S which is extended downwardly near to the bottom of the casing and upon the side walls of this Vertical section 33 in any suitable manner.

The systems of electrical control connections and the contactor system for connecting to the source of power, as illustrated in Figure 19, are also mounted within the vertically extending section 33. Except the main bus bar contactors, they are mounted on the back wall 36 which may be constructed in the form of a door to be swung outwardly to afford access to the compartment 43 in a manner not shown. The contactors connected with the source of power are preferably mounted either upon the partition wall 233 or upon the side wall of section 33. Inasmuch as the particular places and modes of mounting form no part of my invention, they are not illustrated. As disclosed in the diagram of Figure 19 however, there are provided the following electrical control instrumentalities. In addition to the indication and control switches of the order of switches 230, 23| and 235 of the water-cooling control system, there is connected to be operated from each thermostatically-controlled temperature switch 233, a relay 239, the circuit of which is normally closed by switches 230 as long as the temperature of the cooling water is below a dangerously high value. Relays 233 elo-se and maintain closed under conditions of normal water temperature, contacts 246 in a series-control circuit 24|. A relay 242e is controlled by each water-flow control switch 23| (see Figur-e 12 for the relation of switches 230 and 23| to the water-cooling system). The circuits of said relays 242a are closed when the flow of water is established in the cooling system and they in turn close their respective contacts 243 also in the series-control circuit 24|. A relay 243e whose circuit is controlled by the workpiece stock limit switch |14 (see Figures 13 and 18 14) is closed when the workpiece is in place against the stock gauge to in turn close contacts 244 in a second control line 242. Thermostatically-controlled switch 230 closes the circuit of water heater 232 for the cooling of rails 16. The pressure-operated switch 235 places potential on the main bus lines 245, 246 of the control system. Switchboard signal lamps 241 are connected in order, one across the lead-in of the control bus line 245, 246 from the alternatingcurrent low voltage means 248 through line switches 249 in advance of the pressure control switch 235, one across lines 245, 246 behind the pressure switch 235 and illuminated when the pressure switch is closed by turning on the cooling water. The lamp 241 in parallel with the water heater 232 is controlled by the thermostatic switch 230. One such lamp is in parallel with each of the several relays 239, 242a and 243e, respectively indicating the on condition of the associated relay. An anti-reset safety relay 250 circuit is controlled jointly by control line 24| in which all contacts 245, 243 are in series with those of pressure switch 235, and a normally closed contact 25| of the workpiece loading limit switch |14. The normally open switch |14 controls relay 243er. Relay 250 carries a normally open locking Contact 253 and a normally open control contact 254 controlling, in series with contact 244 of relay 243e (the load limit switch relay), the application of potential from bus 245 to control line 242. The three switches 203, 264, and 205 are operated by the door 52 (see Figure 18) when the door is manually closed, switch 263 being a momentary switch or a passing contact switch, while switches 234, 205 remain closed as long as door 52 remains closed. The contactor pilot relay 255 initially receives its potential from control line 242 by way of switches 204 and 203, and then locks up by its normally open locking contact 256 which connects its circuit 251 by bypass 25B around momentary switch 203 and back through switch 204 through the control line 242. The circuit of relay 255 is completed through a conductor 25S and normally closed contact 265 to bus 245. A sequency controller connects contact 26| placing potential as derived from control line 242 by way of switch 204 and branch 258 upon sequency controller 262, which sequency controller is a chronometrically-operated device adapted to apply, in desired timed sequency and in succession with or without overlap of connection, the connection of a multiple number of machines such as the instant one to the same source of power, each machine being connected by program or requirements (disconnection is by means of the individual furnace machines own timing). Contacts 263 of such controller apply potential derived from control line 242 over branch 264 to the timers. Two timers 265 of identical construction are set to start and stop at the same times and thereby to impose simultaneously upon the control circuits and in synchronism the same controlling time intervals. The timer-controlling relays 266 operate over parallel controlling circuits 261 receiving potential from line 264, and having their return circuits connected directly to control bus 245 which is directly extended to the timers. Certain locking contacts 268 are opened by means of unloading the stock which opens load switch |14 which opens relay contact 244 which removes voltage from solenoids 266 permitting spring reset within timers. Motors 269 circuits are closed at normally open contacts 213 when the relays 19 266 are' energized. On relays 27| have their circuits closed by the same contacts 279. Both the on relays 27| and the motors 269, like the timer relays 266, have a return connection directly to bus 245. Off relays 272 are closed at contacts 273 when motors 269 are cle-energized which, like the motors 269 and the on relays 27|, are subjected to potential by way of contacts 274 connecting with the control line 242 which, it will be recalledfderives its potential from control bus 246. Main contactor relay 275 has a circuit 276 derived from control line 242 by way of contacts 277 of relays 27| in series. The return line connection to bus 245 is by way of the normally open switch 295 controlled by the furnace door 52. Signal lamps 247 are connected in parallel with each of the relays 299 and 275. The furnace door latch-releasing sole-- noid 299 (see Figure 18) has its circuit 27B from the control line 242 to the return bus 245 controlled by way of contacts 279 of relays 272 in series. An A. C./D. C. rectiiier 289 shown in diagram derives its power from the A. C. bus lbars. 245, 246 over an extension 26| from the control line 242 by way of normally open contacts 282 of the main contactor control relay 275 which, it will be remembered, also controls contact 255 in the circuit 259 of the pilot relay 255. The main contacter itself 283 controls the application of high-frequency high-power current to coil 49 of the furnace, lwhich main contactor 283 receives its power over D. C. circuit 284 closed by contacts 265 of relay 275. The main contactor contacts v286 are those through which the high-frequency high-power current is cut von and cut on of coil 49, or an intervened transformer supplying coil 49 and any associated condensers.

The operation of the machine is as follows:V

Water having been turned onto the water circuits of Figure 12 in advance, water pressure switch 235 (follow Figures l2 and 19), thermostatic switch 239 of the heater 232, and thermostatic and iiow switches 239 and 23| associated with the remaining cooling fluid circuits, areall closed and the various associated indicating lamps 247 are illumined, showing that they are closed. Should any one of these switches be opened due to the absence of the condition which actuates it, the associated lamp will be out, showing the operator where trouble may lie. Closure of these several switches results in the closure of the circuits of each of the associated relays 239 and 242e, and their closure in turn of their contacts 229, 243, which in series establish the continuity of the preliminary control line 24| which governs the heat control or anti-reset relay 255. Inasmuch as a workpiece has not yet been placed in the machine, contacts 25| of relay 24Bit, which complete the connection of circuit 24| to control bus 255, are still closed. Relay 259, therefore, pulls up and locks itself up past contacts 25| by locking contacts 253. Relay 259 also closes its Contacts 254, thus conditioning control line 252 of the system to receive potential from control bus 226 by way of the still-open contacts 244 of relay 2450i which is under the control of the workpieceactuated switch |74.

The door 52 being in the raised position shown in full lines in Figure 3, a workpiece in the form of a bar of appropriate cross-section and length is introduced through mouthpiece 96. Preferably, in this case, the workpiece is round, and of a length such that, when its inner end is against the inner end of the stock gauge |63, its outer end 2O projects outside of the mouthpiece 96 at a .dis-Y tance beneath the hood-like door 52. The door 52 is then closed downwardly.

Theact of placing the bar in heating juxtaposition to the coil engages its inner end with the tip |47 of the push-out rod |45, moving it rearwardly. This movement carries collar |63 rearwardly, moving locking arm |75 (see Figures 13 and 14, particularly) rearwardly, and, through cam arm |75, closes the loading switch |74. This switch, it will be recalled by reference to Figure 19, closes and retains closed the circuit of relay 2431 which in turn closes its contacts 244 which lie in the control line 242. Control potential thus becomes applied to line 242 through the closed contact 254 of the lock-up heat control relay 256. Simultaneously, relay 243a opens its contacts 25| so that, should heat control relay 259 become deenergized and its now-closed locking contacts 253 be opened, the relay cannot again be energized until the workpiece then in the machine has been removed.

The closing of furnace door 52 downwardly to the dotted-line position shown in Figure 3, engages it with the latch bolt |55 and becomes latched in its closed position, though biased to the open position by spring |94 (see Figure 3).

In moving downwardly, door 52 rocks shaft |95,v

and through arms 267 closes the three microswitches 293, 294, 295. These switches appear in the upper central portion of the diagram of Figure 19. Switches 294 and 295, when closed, remain closed as long as the door is closed. Switch 293 is adjusted for but momentary contact during the final passage of the door to fullclosed position and is thereupon immediately reopened. The door 52 has small amount of overtravel for this purpose, being closed beyond latching position and then drawn back by spring |94 against bolt |95. This backward travel releases switch 293, but switches 294 and 295 remain closed. Thereby pilot relay 255 is energized over its circuit 257, 259 and normally closed contact 269 of contactor relay 275, and pulls up its contacts 26| and 256, locking itself up by the latter through the continuing contact 294 of the group 293, 294, 295 operated by the door. The sduence- 'controlling switch 262 which governs the placement of potential from extension 258 of the control line 242 through contact 26|, to contact 263 of the controller, operates continuously, so placingpotential sequentially upon a series of furnace machines. When the turn of this particular machine comes in the sequence, contact is made at 253 and potential is carried over line 254 and the branch 267 to the starting relays 269 of the pair of timers 255 which jointly control the heating cycle of the machine.

These timers are of the well-known Eagle Signal Corporation type, which, when energized, operate through a predetermined heating cycle period and then automatically close the period.

Relays 266 pulling up, transfer the potential from lines 267 through contacts 274 of the relays to terminals 279, from which there are simultaneously energized the driving motors 269 of the timers and the extension control relays 27|, the latter being energized over branches 27m, both the motors 259 and relays 27| having return line connections directly to the main control bus 245. Relays 27| through their contacts 277 in series close the circuit from control line 242 by way of conductor 276 to contactor relay 275. The motors 269 start the timers upon their adjusted time cycle. Contacter relay 275 reaches control bus 245 through the continuingly closed contacts 255 of the door 52 and is therefore energized. It pulls up its contacts, opening 255 and thereby releasing the pilot relay 255 which may not` be again operated until another cycle is instituted, thereby releasing the sequence controller from all connection with the timers of this particular furnace until the machine has been reloaded. Relay 215 simultaneously closes its contacts 232 and 235 to the rectifier 289, thereby supplying direct current to the contacter magnet` 233 and operating the switch points 286 to connect the source of power on to the coil 45. The actual heating cycle of the workpiece is thus started substantially at the very moment that the timers 255 are started upon their timing cycle.

This heating cycle continues until motors 269 have completed their predetermined cycle of operation. As the motors close their cycle of operation, they operate upon a mechanism not shown here and not necessary to show,` to bring about a movement of contacts 214 away from contact points 21@ under the control of timer relays 266,

and into engagement with contacts 213, without any wise aiTecting the energization of relays 25@ which remain locked up through contacts 258. The break between contacts 214 and contacts 21B not only stops the revolution of the timer motors, but also removes potential from relays 21| which latter, opening their contacts 211, open the circuit of the relay 215, which in turn opens its contacts 282, 285, removing potential from contaotor 283 and cutting off power from coil 48 at switch points 286, thus closing the accurately-timed heating cycle for the workpiece. The movement of contactors 214 against points Z13 at this close of the heating cycle places potential on relays 212. These close their contacts 219 in series, completing circuit 218 to the door latch solenoid 2GB (see Figure 18 again), releasing the door 52 which thereupon flies to its open position shown in full lines in Figure 3, opening its controlled contacts 254, 205. If either timer fails for any reason, the operation of the remaining timer is such as to open the main contacter and interrupt the heating at the proper time.

Thereupon the heated workpiece may be removed simply by pushing downwardly on foot pedal |54 (see igures 1,v 2,` 3, 13, and' 14). This actuates cylinder |58 to rock crank |54 about its axis |55 to engage the upper end of the crank with collar m3 on push-out rod |48, therethrough to push the workpiece axially outwardly. Simultaneously, it may be grasped in suitabletongs and removed for placement in the forging machine cr other instrumentality used to treat or form it. Upon the removal of the workpiece the load switch |14 is opened, de-energizing relay 243e,

opening points 244, and removing potential from control line '.242 and unlocking timer relays 265 at contacts 258. Until relays 255 are unlocked the timers cannot be started upon a new cycle.

All during the heating cycle, the various signal-indicating lamps 241 are illuminated to show that each instrumentality of the controls of a machine is functioning properly. Should any one of them not be functioning properly, the correspending lamp 241 is extinguished and an operator will know precisely where the trouble is to be found. The same, of course, is true at. any time during the operation of the machine, and before the heating cycle is instituted, insofar as those instrumentalities in operation before doors 52 are closed are concerned, as, for example, where those thermostats 235Y closing switches 23|, K

22 water pressure operated switch 235 and the like', are concerned.

If the heating cycle be interrupted through any disorder, through failure of the source or power, failure of water, or the like, relay 252| and its associated circuits come into play to require that the machine be unloaded and again reloaded before it can be again started. This is so because once relay 253', which is self-locked at contacts 25.3, has been de-energized through removal` of power from the control buses 245, 246 or through the. opening of any of the contacts 240, 243, it cannot again be pulled up to condition the control circuit 242 until the workpiece then in the machine has been removed, thereby opening the workpiece limit switch 14 to de-energize relay .2.43ct and close its points 25|. The latter are retained open as long as there is a workpiece in the. machine. This is simply because as long as a workpiece is in the machine, the` push-out rod |48 through collar |63 retains rock arm |15 in its rearward position against the tension oi spring |82, in which cam retains switch arm |8| raised and switch |14 closed. Thus an operator is compelled to notice that a workpiece has been partially heated andk refrains from replacing it in the machine until after it has been cooled. Overheating of a workpiece through subjection to one whole heating cycle and after exposure to a fraction of a prior heating. cycle is thus prevented.

My invention is susceptible of many modifications of its various component. parts and their coacting inter-relationships andV organizations. For example, the heating coil itself may be variously modified. I show in Figure 10 one' such modification in which the rails T6 comprise each two tubular devices welded together in the radial planewhereby to giveV them greater radial depth and stiffness. The retaining clasps 19 and the ns 8|! arev in turn welded to the radially inner such tubular sections. Cooling water is passed through both of the tubular sections. It may be passed down one such tubular section and returned by the other, or it may be passedV through them in parallel as may be desired (suchv con.- nections not beingV shown). This organization of the work-supporting rails permits a greater depth of heat insulating segments 14 and, of course, connotes a larger diameter of coil relative to the diameter of the workpiece, (the latter shown in Figure l0 generally in dot-and-dashlines).

In this description I have described timers 265 as chronometrically-operatedl devices. They might equally well be thermometric-timing devices actuated after that length of time required to heat the workpiece to a determinate temperature through a photocell responsive device of any well-known type.

In connection with the laminated iron utilized in the magnetic` circuit in extension of the axis of the workpiece, one form of this core has been described. The best distribution of heat inthe end of the workpiece (and it is an aim of this laminated iron to secure better distribution of heat in the end of theworkpiece) I conceive to be had when the diameter of the engaging end of the core is less than the diameter ofthe workpiece, by substantially about twice the skin depth of current penetration in the workpiece. A diameter of the engaging end of core about twothirds of the diameter of the workpiece is believed by me to be a, good proportion. Thus two importantY advantages ofthe inclusion ofthe core are conoined, the collecting of the coil flux and 

